Fluid fuel internal-combustion air heater



Dec. 30, @947. H. J. DE N. M COLLUM 2,433,618

FLUID FUEL INTERNAL-COMBUSTION AIR HEATER Filed Feb. 25, 1945 2 Sheets-$heet 1 Wk /ZLM/l/L M Dec. 3, 194-7 H. J. DE N. M COLLUM FLUID FUEL INTERNAL-COMBUSTION AIR HEATER I '2 Sheets-Sheet 2 Filed Feb. 25, 1945 in: me

Patented Dec. 30, 1947 U N I T E D 1 SET l O F F I CE FLUID FUEI INTERNAL-GOMBUSTION -QAIR HEATER l Henry J a De "N1 ltfltit'fiollum; Ghic'ago', 1 11.; "Thelma L :MoColium; 'executrix f s'aid Henry J; De N Mc- Gollumfi deceased; assignor ltdstewart warner 'Gorpo'ration, eGhicago, .lll.,- a rcorporatiom of Virginia Application i ebrilary 25, 1943, Serial No. 477,080

1 Claim. 1

"My .'invention pertains to heaters and more particularly to heaters of the' i'nt'ernalcombustion type.

2 An object or my invention' is-to provide an interhal combustion type foi -heater so constructed u 1- 'thatthe combusti'on bf the'' cornbus'ible' mixture in the combustion chamber cannot flash back into the induction tube through which this mixture is supplied to the combustion chamber. Another object of niy' invention is to: provide a heater-of the 'int'er-nal combustion type wherein the. combustion tube leading to the' combustion chamber --'is -so constructed that r it provides a smooth, rapid: flow of combustible-mixture to the combustion chamber, this flow being "free irom eddy currents: and-"dead pockets-and being at a J rate greaterthan the-rate-of flame-propagation whereby combustion in the iriductiontube isprevented.

iA'n'other object bf 'my invention is to providea 2' heater of the internal combustion type wherein the combustible mixture is delivered to! the combustion chamber in such manner as to form a continuous ring of-flame, therebyperrnittingcomplete' combustion ofthe fuel mixture-m ashort;

compact combustion" chamber.

Another object of my invention is to provide a heater of the: internal combustion type whichwill "provide any desireddegree of "preheating :"of the combustible mixture and which isequally ad'apted for use with-light andhe'avy fuel.

' Another "obj ect for my invention is to provide a heatertofthe internalc'ombustion type' which is lightrin weight,efficient-compact; inexpensive to manufacture; srieliable; and capable of-giving long and trouble-free service.

Other objects and advantages will become apparent as the description proceeds.

. of the type disclosed-and claimed-in:- my' co pending' application; Serial No. 464,45 .1;.-fi1ed Novem- -ber 4', 1942Patent No. 2,380,602. l The heatex- 1 changer 2 is' of 1 tubular shape and has longitudinallyexter'lding' flues 24 throughwhich the 1 hot gases from" thecomb-usti'on chamber pass on 'theirwayto'an outlet chamber 26. The outlet chamber 26 communicates with atmosphere through-an outlet fitting 28 and anysuitable exhaust pipe' attach'ed 'to" the threaded end 30 0f this fitting.

1A :mumerez is located in the tubular heat exchanger--22 and comprises asheet metalshell- 34 having narrow slots 36 forming acoustic conplings betweenthe flues '24 and the interior of theumuffier shell whereby sound-may pass into this shell and be absorbed by the sound absorbing material =38 -contained' therein. This sound absorbingmoJteri'al may be stainless steel W001 or glass wool; or any other suitable sound absorbing material. 'The muflier 32 is provided with a nose 4B which aids in directing the hot products of combustion"- into theflues 24 and an empty acoustic chamber" is formed in this nose and communicates with the-interior of the main portionof the muffler 'by way of openings 44.

I As-the hot gases from the combustion chamber travel lengthwise of the flues 24, these gases give I up' heatito 'the 'heat eXchanger'ZZ. This heat ex- I chan'ger hasfins '46 projecting into the stream of ventilating J air which is directed over the fins by a casing fiB surrounding the combustion chamber 20 and heat exchanger 22. As this ventilating air passes over the fins 46, it is heated and the heated air-'passes' from the lefthand end of the v:casingp lii into a space to be heated or into a duct system having selected outlets'in such space or spaces.

:Air for ventilating purposes and for supporting :combustioninthe combustion chamber 20 is supplied to:arighthand end of the casing 48 by a ram; blower orany other suitable means. Most of. thisair passes 'overthe finned heat exchanger 22-1:and .providest=heated ventilating air for the :spaceor spaces to be heated. "Part of the air sup- ;apliecl toi'the casing" 48, however, enters the inlet "-end 50 (Figs.-'2- and i) of apipe 5i'1eading to a r1 carburetor'indicated generally by reference charactor-:52. 'L'I-his carburetor is provided with the 1 usual V'enturi tube 54 having a restricted throat in Whichthe'fueLjet-EG is located. This fuel jet has a pipe 58 which extends down into and near the bottom of -a conventional float bo'wl'fifl. A

1 pipe 62 connects #the float bowl with any suitable source of fuel.

v The upper 'p'a'rt of the float bowl is connected by pipe 64 with thepipe 5! so that the pressure difierential between the pipe 51 and throat of the Venturi tube is available to lift fuel from the float bowl 60 to the jet 56 and discharge it through the openings in this jet into the air flowing through the throat of the Venturi tube 56. The mixture of fuel and air formed in the Venturi tube 54 is delivered to the induction tube 65 which passes through the casing 48 and into the combustion chamber 28. A plate 68 is removably attached to the casing 48, partially to cover an opening in this casing which permits insertion and removal of the induction tube 66. Where this tube passes through a wall of the combustion chamber 20, the tube is preferably welded or soldered to the combustion chamber wall, as indicated at H3, to form a gas-tight joint therebetween.

The induction tube 66 has a smooth interior which is free from obstructions or pockets and which p rmits a smooth flow of the combustible mixture therethrough. This induction tube is of such diameter that the rate of flow of the combustible mixture therethrough is faster than the rate of flame propagation so that in normal operation of the heater no combustion takes place in the induction tube. If, for any reason, the rate of flow of combustible mixture in the induction tube should be reduced temporarily so that combustion would take place in this tube, as soon as the normal rate of flow of the combustible mixture is restored, the burning gases Will be driven from this tube into the combustion chamber and continuance of combustion in the induction tube will be avoided. The smooth, uniform diameter of this tube is an important factor in this regard, since it prevents the formation of eddy currents or pockets where combustion could continue because the rate of flow in these eddy currents would be less than the rate of flame propagation.

In the normal operation of the heater, the coinbustible mixture does not burn until after it has moved an appreciable distance beyond the discharge end H of the induction tube. The part it of this induction tube which lies within the combustion chamber 25 forms a means for preheating the mixture of fuel and air to any desired degree before this mixture is ignited. In Fig. 2, the preheating portion 74 of the induction tube is shown as extending through an arc of somewhat more than 99 which affords ample preheating where the heater is operated with gasoline or other relatively light fuels.

Because of the curvature of the portion i l of the induction tube, the mixture delivered to the combustion chamber whirls about the longitudinal axis of this chamber, as clearly indicated by the arrows in Fig. 2. The curved portion 14 of the induction tube, however, does not necessarily lie in a plane perpendicular to the axis of the combustion chamber and in the particular embodiment shown the end portion of this tube is inclined, as shown in Fig. 1, to direct the combustible mixture toward a pocket 76 formed at one end of the combustion chamber. The electrical igniter 18 communicates directly with this pocket which receives fresh combustible mixture from the induction tube, but slows down the rate of travel of this mixture to such an extent that it may be easily ignited.

The electrical igniter is may operate continuously. However, in heaters Of this type it is usual to connect this igniter with its source of current through a thermostatic switch which cuts out the igniter after the heater has attained normal opcrating temperature and where this is done it is common to use a re-igniter to maintain combustion thereafter. I have indicated such a re-ignitcr by reference character 89, although in heaters embodyingmy invention such a re-igniter is not essential since the ring of flame in the combustion chamber is sufficient in and of itself to maintain combustion after the electrical igniter 18 has cut out. This ring of flame starts a short distance beyond the end 80 of the induction tube and continues around the inner surface of the annular wall of the combustion chamber and overlaps this end 88 to form an unbroken ring of fire which ignites the mixture flowing from the end of the induction tube.

The whirling motion of the mixture entering the combustion chamber and the inclination of the outer end of the induction tube toward the rear wall of this chamber insure complete combustion of the mixture within a very short combustion chamber. This short combustion chamber reduces the total length of the heater and also reduces the weight of the heater. Since the walls of the combustion chamber are directly exposed to the ventilating air, all heat which passes into these walls is transferred to the ventilating air and is thus efiiciently used and does not represent a loss.

The induction tube has a smooth inner surface which eliminates eddy currents of small velocity which would support combustion in the normal operation of the heater. The diameter of the induction tube is so selected that the rate of flow of combustible mixture therethrough is faster than the rate of flame propagation, so that no combustion takes place in this tube during normal heater operation. If, for any reason, the rate of flow of the combustible mixture in the induction tube should be temporarily reduced sufficiently to permit combustion to take place in this tube, all burning gases will be immediately discharged from the induction tube as soon as normal flow of combustible mixture is restored.

That part of the induction tube lying within the combustion chamber may be made of any length to give the desired preheating and is preferably of such length that the mixture entering the combustion chamber is preheated to such a degree that it will burn cleanly and quickly as soon as it is ignited. This feature, together with the circular motion of the combustible mixture in the combustion chamber and the resultant ring of flame, permit complete and efiicient combustion in a combustion chamber of short length and without increasing the diameter of the combustion chamber over that commonly used in such heaters.

Because of the provisions for obtaining any desired amount of preheating of the combustible mixture, my novel heater is equally adapted for use with kerosene, fuel oils and other relatively heavy fuels, as well as gasoline and other light fuels.

It is to be understood that my invention is not limited to the details shown and described, but may assume numerous other forms and that the scope of my invention is defined in the following claim.

I claim:

A heater of the class described having heat exchange means, comprising means forming a combustion chamber, means connecting said combustion chamber with said heat exchangemeans for the delivery of hot gases thereto, means including an induction tube of substantially uniform diameter for supplying a combustible mixture to said chamber, said chamber having a cylindrical wall merging with an end wall to form a pocket, said induction tube having a portion extending into said chamber and curved about the axis thereof, said curved portion being inclined with respect to said axis and having an outlet end directed toward said pocket, and an electrical igniter for igniting combustible mixture in said pocket.

HENRY J. DE N. McCOLLUM.

REFERENCES CITED The following references are of record in the file of this patent:

Number UNITED STATES PATENTS Name Date Shearman et a1. Feb. 13, 1912 Uschold et a1. July 1, 1941 Morris et a1 May 22, 1928 Carlson et a1. Nov. 13, 1928 Frentzel Nov, 28, 1933 Thompson Nov. 2, 1920 Smith Sept. 24, 1940 Runkwitz June 2, 1931 Good Oct. 25, 1921 

